Centrifuge rotor

ABSTRACT

A centrifuge rotor having a plurality of chambers each comprising (1) a socket extending through the top surface of the rotor having an inside cylindrical surface terminating in a spherical surface, (2) a slot extending through the peripheral and bottom surfaces of the rotor that is formed by a cylindrical section extending through an arc of 90* with a center along the vertical axis of the socket and below the center of the socket spherical section and (3) a spherical seat connecting the slot and the socket having its center along the horizontal axis of the slot so that the angle between the vertical axis of the rotor and a line between the center of the spherical socket section and the seat is between 55* and 90*. Buckets adapted to fit into the chambers and move between a vertical and horizontal position comprise a top spherical flanged section and a bottom tubular section.

United States Patent Scanlon 1 Aug. 29, 1972 [54] CENTRIFUGE ROTOR [57]ABSTRACT [72] Inventor: Mic -L S 0 .M A centrifuge rotor having aplurality of chambers each 73 A 1 D C N comprising (1) a socketextending through the top sslgnee 2:22: g j t eedham surface of therotor having an inside cylindrical surface terminating in a sphericalsurface, (2) a slot exl Flled! J 1971 tending through the peripheral andbottom surfaces of Appl. No.: 104,599

Primary Examiner-Jordan Franklin Assistant ExaminerGeorge H. KrizmanichAtt0rneyKenway, Jenney & Hildreth the rotor that is fonncd by acylindrical section extending through an arc of 90 with a center alongthe vertical axis of the socket and below the center of the socketspherical section and (3) a spherical seat connecting the slot and thesocket having its center along the horizontal axis of the slot so thatthe angle between the vertical axis of the rotor and a line between thecenter of the spherical socket section and the seat is between 55 and90. Buckets adapted to fit into the chambers and move between a verticaland horizontal position comprise a top spherical flanged section and abottom tubular section.

4 Claims, 3 Drawing Figures Patented Aug. 29, 1972 INVENTOR MICHAEL F.SCANLON TORNEYS CENTRIFUGE ROTOR This invention relates to a centrifugerotor and to a combination of the centrigue rotor and detachably mountedbuckets.

In present centrifuge rotors, buckets are pivotally mounted on therotors to permit their movement to a horizontal position when the rotoris spinning and back to the vertical position when the rotor is at rest.In one type, the rotor periphery is formed with an outwardly disposedflange having circumferentially spaced vertical slots shaped toaccommodate a bucket. The buckets are provided with trunnions having aremovable closure that fits into undercut shoulders of the slot toconfine them during centrifugation. Proposals for increasing thestrength of the pivotal connections have led to increased weight in therotor which reduces the safe operational rotor speed.

It has been proposed to eliminate this additional construction byproviding slots within the rotor shaped to retain buckets whilepermitting them to pivot between the vertical and horizontal positions.These sockets extend vertically from the bottom surface of the rotor asufficient distance to permit insertion of the bucket having a sphericalshaped flange. A seat, that accommodates the spherical flanged portionof the bucket, extends radially outwardly from the socket to the rotorperiphery and is shaped to permit horizontal movement of the bucket. Thebuckets are placed into the rotor through the bottom surface upwardlyinto the socket and then outwardly onto the seat. It is difficult forthe operator to see whether the bucket has been placed correctly intothe seat which results in frequent incorrect placement. When incorrectlyplaced, the bucket will be jarred into the correct position after rotorstartup, rather than moving smoothly between the vertical and horizontalpositions, thereby disturbing the sample and gradient, increasing thetime needed for the desired separation and disturbing any interfaceformed during centrifugation. A further undesirable aspect of incorrectplacement is the danger that the bucket will be detached from the rotor.

In accordance with the present invention, there is provided a rotorhaving a socket construction which permits visual observance of bucketloading. The buckets comprises a lower tubular portion and an upperflanged portion having an outer spherical surface with its centercoaxial with the vertical axis of the tubular portion. The socketcomprises a cylindrical hole extending vertically from the top surfaceof the rotor and terminating into a spherical surface having the samediameter as the cylinder. The socket is intersected by a slot extendingthrough the peripheral and bottom surfaces of the rotor and is formed bya cylindrical section extending through an arc of 90 with the center ofthe are being along the vertical axis of the socket and below the centerof the socket spherical section. The diameter of the slot issufficiently large to accommodate the tubular portion of the bucket butsmaller than the bucket flange. A spherical seat connecting the slot andthe socket has its center along the horizontal axis of the slot, and hasthe same or slightly smaller diameter as the spherical surface of thesocket. The center of the spherical seat is slightly below the center ofthe spherical section of the socket so that an angle formed by the linebetween the two centers and the vertical axis of the rotor is betweenabout 55 and about 90; preferably between and The cavities in the rotorare evenly spaced around its circumference so that the rotor is balancedwhen fully loaded. The buckets are placed in the rotor sockets byinserting the buckets, tubular portion down, through the socket and theslot so that the spherical flange is seated in the spherical section ofthe sockets. When the rotor is spun, the flanged portion of the bucketslides along the spherical seat allowing the bucket to pivot from thevertical to the horizontal position.

The invention will be more fully described herein with reference to theaccompanying drawings.

FIG. 1 is a top plan view, in partial cross section, of a rotor of thisinvention.

FIG. 2 is a vertical cross-sectional view of the rotor of FIG. 1 takenalong line 22.

FIG. 3 is a cross sectional view of a bucket employed in conjunctionwith the rotor of this invention.

The buckets shown in the figures are generally indicated at 10. Eachbucket 10 includes a tubular portion 11 closed at one end and having itsother end counter bored to provide a seat 12 for a seal 13 and threadedto receive a cap 14. The bucket 10 is provided with a spherical flange15 with an outer surface that converges toward the center of the bucket10. Each tubular portion 11 can be externally tapered to achieve anoptimum strength to weight ratio. The taper is slight since the bucketwalls are relatively thin and the inside diameter of the tubular portion11 is constant. However, the use of a tapered bucket is not essential tothis invention.

The rotor 16 has central bore 17 to receive a centrifuge spindle, notshown. The bore 17 can be modified in any manner to accommodate adriving means, such as the diametrically disposed channels 17a shown inthe figures. The rotor 16 has a plurality of evenly spaced sockets 18that extend into the rotor 16. The bottom portion of the socket 18 isopen to a slot 19 that extends from the peripheral surface 20 of therotor 16. The diameter of the slot 19 is slightly larger than theoutside diameter of the tubular portion 11 of the bucket 10 at theintersection of the flange l5 and the tubular portion 11. Thus, when therotor is at rest, the tubular portion 11 of the bucket 10 hangs freelythrough the slot 19 while the spherical flange 15 rests in sphericalseat 26. When the rotor 16 is spun, the bucket 10 is pivoted about thespherical flange 15 to the horizontal position as shown in FIG. 2 by thedotted lines.

The socket 18 is formed with a spherical cutting tool to cut acylindrical hole which terminates in a hemisphere 25. The slot 19 thenis formed with a spherical cutting tool which develops a continuousclearance from the bottom surface of the rotor to the periphery of therotor and intersects the socket. After the slot is formed, a sphericalcutting tool of slightly smaller radius than the socket sphericalcutting tool is inserted in the socket and moved radially outward anddown at a constant angle to form the seat 26.

As shown in FIG. 2, the cylindrical socket 18 has a vertical axis 27 andat the bottom thereof a spherical section 25 which spherical section hasa center 28 along the vertical axis 27. A slot 19 extending from theperpherical and bottom surfaces of the rotor 16 comprises a cylindricalsection extending through an arc of about which cylindrical section hasa center 29 on the vertical axis 27 of socket 18. A spherical seat 26connects the socket 18 and the slot 19. The spherical seat has a center30 on the horizontal axis 31 of the slot. The line between centers 28and 30 forms an angle, a, between about 55 and 90 with the vertical axis32 of the rotor 16.

The rotor of the present invention provides substantial advantages inthat the buckets can be placed in proper position easily and quickly sothat a smooth transition of the bucket is attained when moving betweenthe vertical and horizontal positions when the rotor is driven.

I claim:

1. A rotor having a top surface, a bottom surface and a peripheralsurface, a plurality of chambers evenly spaced around the circumferenceof said top surface and said bottom surface and being equidistant fromthe vertical axis of said rotor, each of said chambers comprising a. asocket extending through the top surface having an inside cylindricalsurface terminating in a spherical section b. a slot extending from saidperipheral and bottom surfaces, said slot comprising a cylindricalsection extending through an arc of about 90 with a center along thevertical axis of the socket and below the center of the socket sphericalsection, and

c. a spherical seat connecting the slot and the socket having its centeralong the horizontal axis of the slot so that the angle between thevertical axis of the rotor and a line between the centers of thespherical section and the seat is between 55 and 90.

said rotor having a top surface, a bottom surface and a peripheralsurface, a plurality of chambers evenly spaced around the circumferenceof said top surface and said bottom surface and being equidistant fromthe vertical axis of said rotor, each of said chambers comprising a. asocket extending through the top surface having an inside cylindricalsurface terminating in a spherical section b. a slot extending from saidperipheral and bottom surfaces, said slot comprising a cylindricalsection extending through an arc of about 90 with a center along thevertical axis of the socket and below the center of the socket sphericalsection,

c. a spherical seat connecting the slot and the socket having its centeralong the horizontal axis of the slot so that the angle between thevertical axis of the rotor and a line between the centers of thespherical section and the seat is between 55 and 90.

d. buckets having a tubular portion closed at one end and a flange atthe other end, said flange having an outside spherical surface that fitsinto the spherical sections of said socket and said slot and saidtubular portion extending through the peripheral and bottom surfaces ofsaid rotor.

3. The rotor of claim 1 wherein the angle between the vertical axis ofthe rotor and a line between the centers of the spherical section andthe seat is between and 4. The rotor of claim 2 wherein the anglebetween the vertical axis of the rotor and a line between the centers ofthe spherical section and the seat is between 70 and 75.

1. A rotor having a top surface, a bottom surface and a peripheralsurface, a plurality of chambers evenly spaced around the circumferenceof said top surface and said bottom surface and being equidistant fromthe vertical axis of said rotor, each of said chambers comprising a. asocket extending through the top surface having an inside cylindricalsurface terminating in a spherical section b. a slot extending from saidperipheral and bottom surfaces, said slot comprising a cylindricalsection extending through an arc of about 90* with a center along thevertical axis of the socket and below the center of the socket sphericalsection, and c. a spherical seat connecting the slot and the sockethaving its center along the horizontal axis of the slot so that theangle between the vertical axis of the rotor and a line between thecenters of the spherical section and the seat is between 55* and 90* .2. In combination, a centrifuge rotor and buckets, said rotor having atop surface, a bottom surface and a peripheral surface, a plurality ofchambers evenly spaced around the circumference of said top surface andsaid bottom surface and being equidistant from the vertical axis of saidrotor, each of said chambers comprising a. a socket extending throughthe top surface having an inside cylindrical surface terminating in aspherical section b. a slot extending from said peripheral and bottomsurfaces, said slot comprising a cylindrical section extending throughan arc of about 90* with a center along the vertical axis of the socketand below the center of the socket spherical section, c. a sphericalseat connecting the slot and the socket having its center along thehorizontal axis of the slot so that the angle between the vertical axisof the rotor and a line between the centers of the spherical section andthe seat is between 55* and 90* . d. buckets having a tubular portionclosed at one end and a flange at the other end, said flange having anoutside spherical surface that fits into the spherical sections of saidsocket and said slot and said tubular portion extending through theperipheral and bottom surfaces of said rotor.
 3. The rotor of claim 1wherein the angle between the vertical axis of the rotor and a linebetween the centers of the spherical section and the seat is between 70*and 75* .
 4. The rotor of claim 2 wherein the angle between the verticalaxis of the rotor and a line between the centers of the sphericalsection and the seat is between 70* and 75* .